Beginning of a dialog window, including tabbed navigation to register an account or sign in to an existing account. Both registration and sign in support using google and facebook accounts. Escape will close this window.

that was happening to me a few days ago and i kind of understand.
if you were just favoriting by clicking the heart icon, it might not be working well. try going the original route of clicking on the item you want to favorite and selecting "add to favorites". should work fine.